>The transformation used to represent the physically linear intensity data either generated synthetically via an algorithm or captured by a linear device (such as a CMOS of a digital camera or a scanner) with the discrete values of the perceptually linear scale is called gamma encoding.

This isn't super correct, and it underscores the biggest issue in this article:

sRGB (and its gamma encoding function) has absolutely nothing to do with perceptual linearity. sRGB is not perceptually linear! The original gamma encoding as far as I'm aware was made to compensate for the nonlinear transfer function of CRTs back in ye olde days. Its true that human vision is nonlinear, but sRGB is not a particularly good match to the perceptual linearity of human vision. Its a really common error to make, and leads to people wondering why we can't use sRGB to blend in if the reason why it was invented is because its perceptually linear

The article goes to compound on this mistake, which is why this is such a problematic misconception:

> Interestingly, Photoshop antialiases text using γ=1.42 by default, and this indeed seems to yield the best looking results (middle image). The reason for this is that most fonts have been designed for gamma-incorrect font rasterizers, hence if you use linear space (correctly), then the fonts will look thinner than they should.

This is where the mistakes start to add up

Consider what you're trying to achieve during antialiasing: when rasterising a line, lets say we discover that a pixel is only 40% covered and want to darken it. This means that we want our pixel's brightness to decrease by 40% to a human being. We don't want to emit 40% less light, because that's not what antialiasing is trying to achieve!

Both sRGB and linear colour are the wrong colour spaces to use. You want to blend in a perceptually linear colourspace, and photoshop's 1.42 gamma exponent probably maps better to human vision than 2.2 or 1.0 while being cheaper than a LUV conversion

>The standard gamma (γ) value to use in computer display systems is 2.2. The main reason for this is because a gamma of 2.2 approximately matches the power law sensitivity of human vision

The gamma transfer functions are also wrong. Its worth getting hung up on because it actually causes nontrivial errors, especially in the age of hardware accelerated sRGB conversions where doing it correctly is free

This is why when these older games crashed on your PC, the monitor would look all washed out due to the manual gamma adjustments the game made that didn't get restored.

https://www.youtube.com/watch?v=LKnqECcg6Gw

What every coder should know about gamma (2016) - https://news.ycombinator.com/item?id=27721094 - July 2021 (50 comments)

What every coder should know about gamma - https://news.ycombinator.com/item?id=12552094 - Sept 2016 (183 comments)

It's interesting how this part of the trade-off changes when using float16 for color components (as is common when HDR is involved) rather uint8.

Good timing that Safari 27 adds support for srgb-linear and display-p3-linear color spaces.

I felt the first one looked more even. On the first I could tell the difference between every two adjacent bars. On the second one I couldn't tell any difference between the first 4-5 bars.

Can’t reproduce. Tested on two monitors on my desk, designer-targeted Benq and cheap laptop. On the Benq, darkest 3 segments are indistinguishable, the 4-th one barely distinguishable. On the laptop, darkest 4 segments are indistinguishable, the 5-th barely distinguishable. However, on the “emitted light intensity” all bars are clearly visible.

> Image resizing

“Unsurprisingly, C gives the correct result” On my computers B very similar to A, just a tiny bit darker. While the “correct” C result is a lot lighter than A.

Also from the same section:

> B the result of resizing the pattern by 50% directly in sRGB-space (using bicubic interpolation)

Bicubic interpolation is only applicable when enraging images; downsampling is very different problem from interpolation.

Technically, this is not always incorrect, if your working color space is linear and 0 is no light. The problem only comes if you hand that same data to routines or surfaces expecting sRGB or another nonlinear color space (or one where 0 is not no light).

at the fundamental level, if a surface is illuminated with one lightbulb and we add another light bulb, the difference is exteremely noticeable to the human eye. if we add one more lightbulb to a surface that is already illuminated by a hundred light bulbs, there will be no perceptible difference. the exact response can be modeled with a pretty simple power law (with a modification in the low range, as the article mentions).

that's all there really is to "gamma correction". it's a hack that exploits this quirk of the human visual system in order to more efficiently allocate bits for encoding different "lightness" values.

all of the confusion and bugs stem from one or more of the systems in the chain that forms the final image, making an incorrect assumption about what the others are doing. it's a bit like coordinate spaces in that regard.